WASHINGTON — A small group of Chinese satellites in geosynchronous Earth orbit (GEO) made at least 75 “unusual” maneuvers over the past nine years — moving in ways that are consistent with, if not necessarily indicative of, four types of military or intelligence operations, according to a new analysis by the Center for Strategic and International Studies (CSIS).
“These satellites exhibit distinct, categorizable behavior types that are unprecedented in GEO, and each pattern raises different questions about intent,” the study, titled “New Rhythms in GEO: A Quantitative Analysis of Unusual Behavior in Geosynchronous Orbit by Chinese Satellites, 2016-2025” and released today, asserts.
The study, based on a mix of US Space Command data, Chinese-language media and research literature, pinpointed eight Chinese birds that have made frequent maneuvers and/or exhibited “unusual behavior” in the GEO belt some 36,000 kilometers in altitude — an orbital region where many high-value Western military and commercial communications satellites are stationed, along with Pentagon missile warning birds and National Reconnaissance Office satellites for gathering signals intelligence (SIGINT).
The movements of eight of those satellites have been tracked and published on Space-Track.org, the public space object catalog maintained by the US Space Command’s 18th Space Defense Squadron — out of a total of 109 Chinese birds in the database. The movements of a ninth Chinese satellite, SJ-25, have been tracked by independent sky watchers but as of now no data about its orbital parameters has been published by either the US or Chinese governments.
While the moves by those satellites have been documented individually in the past, the CSIS analysis was able to discern what it called four different patterns of movement by eight of the satellites and link those movements to potential military and intelligence gather missions. The CSIS study stresses that it is not possible to know for certain that what exactly the Chinese birds are up to as they roam the heavens. However, the assessment finds that their maneuvers are not random, and match those that would enable certain military missions, including communications, reconnaissance, signals gathering and satellite refueling.
“The frequent movers can be batched into four categories based on the nature and timing of their movements: the Larks, the Skyliners, the Drifters, and the Ink Spots,” the analysis explained.
ChinaSat-20A, launched in 2010 and now defunct, is characterized as a “Lark;” that is, a “moving communications satellite.” Chinese state media has characterized ChinaSat-20 as a civil comsat operated by the state-owned China Satellite Communications Group Co., Ltd. However, CSIS notes that a number of Western analysts, as well as NASA, have concluded that it is more likely to be a military comsat. These sources note that China Satellite Communications Group does not list it among their satellite fleet providing services. Further, neither the firm nor the Chinese government has provided any detail about the ChinaSat-20A’s capabilities.
Three of the nine Chinese satellites, SJ-17, SJ-20, and TJS-3, are characterized as “Skyliners.” These birds “exhibit a history of frequent stair-step maneuvers throughout their lifetimes. They could be moving to park next to foreign communications satellites for signals intelligence purposes, but it is difficult to verify.” CSIS likens their movements to those of Russia’s Luch/Olymp, which US and NATO officials have alleged are stalking Western satellites to eavesdrop.
The study tags the SY-12-01 and SY-12-02, both launched in 2021, as a “Drifter” satellite. “Drifter patterns are characterized by slow, constant sweeps across a set longitudinal band,” the study explains. As the name suggests, these birds don’t use electric propulsion to move quickly but instead just drift along an unusual path in the GEO belt.
“SY-12-01’s longitudinal series … displays an archetypal Drifter pattern. It wanders across the Eastern hemisphere, starting at 94.25 degrees east longitude above western China and drifting further west to Eastern Europe, before flitting back eastward past Siberia and then switching directions to repeat the pattern,” it adds.
The CSIS study found that the SY-12-02 and SJ-23 satellites also exhibit this type of “alternating drift pattern, starting out moving eastward or westward and then drifting the opposite direction over a period of months,” stressing that there “is no obvious mission justification for this behavior, which is unprecedented for satellites in GEO.”
However, the study notes, one likely explanation put forth by experts consulted by CSIS is that the satellites “could be surveying all of the GEO satellites over Asia, possibly for intelligence or space situational awareness purposes.”
Finally, CSIS dubs satellites that move in ways that “do not yet fit neatly” into the other categories as “Inkspots.” SJ-25, which according to Chinese state media is designed to test and verify “satellite fuel replenishment and life extension service technology,” is placed into this category.
“Since its launch in January 2025, SJ-25 has not displayed any station-keeping or periodic drifting behavior. From January to June, it hovered unevenly between 118 and 122 degrees east longitude. From June 10 to 14, SJ-25 rapidly shifted to 127.4 degrees east (over eastern China), to rendezvous with and refuel SJ-21, which arrived at 127.6 degrees east on June 5,” CSIS elaborates.
While neither the Chinese nor US governments have confirmed any details of the SJ-25’s operations, observations by independent sky watchers indicate that the satellite “may be the first satellite to refuel another spacecraft in orbit,” the study asserts.
The CSIS study concludes by urging more study of Chinese satellite maneuvers, and notes that a great deal of open source information is available from Chinese language sources and Chinese government publications.
